--- a/src/core/ngx_rbtree.h
+++ b/src/core/ngx_rbtree.h
@@ -50,9 +50,16 @@ void ngx_rbtree_insert_timer_value(ngx_r
     ngx_rbtree_node_t *node, ngx_rbtree_node_t *sentinel);
 
 
+#define ngx_rbt_red(node)               ((node)->color = 1)
+#define ngx_rbt_black(node)             ((node)->color = 0)
+#define ngx_rbt_is_red(node)            ((node)->color)
+#define ngx_rbt_is_black(node)          (!ngx_rbt_is_red(node))
+#define ngx_rbt_copy_color(n1, n2)      (n1->color = n2->color)
+
+
 /* a sentinel must be black */
 
-#define ngx_rbtree_sentinel_init(node)   node->color = 0
+#define ngx_rbtree_sentinel_init(node)  ngx_rbt_black(node)
 
 
 static ngx_inline ngx_rbtree_node_t *